Astronomers have ruled out any possibility of an asteroid-Earth collision, but the event in Russia and the (unrelated) flyby of asteroid 2012 DA14 highlight the potential danger of primordial material orbiting in our cosmic neighborhood, according to the BBC. What threat does the Earth face from space debris?
There is no danger from 2012 DA14, but what would happen if we were hit by an object of a similar size?
It is not known for sure what 2012 DA14 is made of. However, asteroids less than 100 meters in diameter and composed of rocky material – usually break up high in the atmosphere.
Pieces of rock or meteorites, which constantly fall on our planet as rain, move extremely fast, approximately tens of kilometers per second.
But sometimes, one of those "explosions" can happen close enough to the surface to cause serious damage.
An asteroid or comet with a diameter of several tens of meters exploded about 10 km above Siberia. The blast flattened about 80 million tree trunks near the Tunguska River, fortunately in a sparsely populated area.
However, the same event over a densely populated area would have catastrophic consequences, so media writing that asteroid 2012 DA14 is large enough to level a city is not an exaggeration.
An object similar in size to 2012 DA14 in Arizona made a 1,2 km diameter depression known as Meteor Crater. The object was metallic – composed of iron and nickel – so it was relatively intact when it reached the ground.
How can pieces of rock or metal have such a strong effect?
Pieces of rocks or meteorites, which constantly fall on our planet as rain, move extremely fast, approximately tens of kilometers per second. As mentioned earlier, most of them simply burn up in the atmosphere, while those that manage to fall to the ground have their speed drastically reduced due to atmospheric friction.
The collision that caused the extinction of the dinosaurs 65 million years ago most likely caused an object about 10-15 kilometers wide
This happens because the kinetic energy of a rock from space is the product of half its mass and the square of the speed at which it is moving. In other words, if you double the speed of an object, its kinetic energy will quadruple.
Although there are other factors that determine the effects of an asteroid impact (such as the angle of impact and the geological nature of the substrate), it is not difficult to see why the energy released by the explosion of larger space rocks can be many times stronger than that produced by nuclear weapons.
Researchers from the American Purdue University and Imperial College London have also created a website where users can enter the asteroid's parameters and find out what effects they could have if they hit the Earth.
How big can they be?
The asteroid that flew past our planet is actually small, compared to some. The collision that caused the extinction of the dinosaurs 65 million years ago most likely caused an object about 10-15 kilometers wide.
That space rock hit Mexico's Yucatan Peninsula. Scientists estimate that the explosive energy caused by the impact was equal to the energy released by 100 trillion (thousand billion) tons of TNT, which is several billion times more explosive than the atomic bombs dropped on Hiroshima and Nagasaki.
The huge crater left behind by this event has a diameter of about 180 kilometers and is surrounded by a ground fault 240 kilometers in diameter.
While rocks the size of 2012 DA14 can have a devastating effect on a regional scale, the effects of the asteroid impact on the Yucatan Peninsula were global and long-term.
Initially, the impact caused huge fires, earthquakes and landslides, which resulted in tsunamis. Then hot rocks and gas were released in jets into the atmosphere, enveloping the planet in darkness. There is evidence of significant cooling after the asteroid impact; this "impact winter" could last about 10 years.
If an object of this size were to hit the Earth today, it would probably wipe out civilization.
What can be done if scientists discover that something is headed our way?
One of the best strategies for dealing with an approaching asteroid - which Bruce Willis used in the movie "Armageddon" - is to detonate a nuclear weapon near the surface of the object or below it.
Apart from detaching a large chunk from the object itself, we would hope that the explosion would have deflected the asteroid from its path towards Earth. However, if we were unlucky, this could cause the space rock to break up, sending more pieces flying towards our planet.
Asteroid 2012 DA14 flew by on Saturday at 20.24:27.800 p.m. at a distance of XNUMX kilometers from Earth and continued to move away from it, NASA announced on its website.
If there was more time, a spaceship could be sent to intercept a space rock and nudge it slightly off course. Pointing a laser at the asteroid's surface could also be a way to repel the rock.
Perhaps the most surprising idea is to shoot the balls with a bright color instead of the object to increase its reflection. The pressure of the particles bouncing off the reflective surface would, acting for a long time, divert the rock from its original path.
However, there is no set schedule yet for Don Quixote or any other mission to test asteroid-repelling strategies.
Asteroid flew by the Earth
Asteroid 2012 DA14 flew by on Saturday at 20.24:27.800 p.m. at a distance of XNUMX kilometers from Earth and continued to move away from it, NASA announced on its website.
As previously announced, the asteroid also passed below the orbit where meteorological and telecommunication satellites orbit, but far above the vast majority of satellites, including the International Space Station (ISS), which orbits the Earth at an altitude of about 350 km.
NASA Near Earth Object (NEO) program astronomers Paul Chodas and Don Yeomans said the asteroid passed Earth at about 7,8 miles per second in a south-to-north direction.
The mass of asteroid 2012 DA14, which was discovered a year ago by Spanish astronomers, is 130.000 tons.
Celestial bodies of similar size fly by the globe at a relatively short distance approximately every 40 years, but this asteroid came closest to Earth.
Scientists believe that disasters due to the fall of similar asteroids on the earth's surface occur on average once every 1.200 years.
In the case of falling to the surface, the asteroid would cause consequences comparable to the explosion of a nuclear bomb with a power of 2,5 megatons.
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